Topband: SB-1000

[Tom W8JI]

> If you can't find the exact value of 170pf  the ceramic 5KV door knobs at 
> 200pf will work.  Better yet even a couple of 500pf door knobs in series 
> will give you 250 pf which will just mean a little less on your variable 
> will tune.  Another common ceramic door knob value is 500pf and three in 
> series will put you in the ball park.

NO.

170 pF was used because at 200 pF the capacitor breaks over into a different 
temperature coefficient. You will go from a N750 or so TC to up near or 
above N2000.

This will make the tuning drift with temperature.

Use the original part or parallel smaller values with the same or lower 
TC's. Also be ware the number on the case is often not met. Sometimes the 
caps cannot meet the stamped TC numbers. This is because the clay formula 
used is difficult to make temperture stable.

Just buy the correct part.